View source for RDS-6s

{{Short description|1953 Soviet atmospheric nuclear test}}
{{Infobox Nuclear weapons test
|name                =Joe-4<br/>''RDS-6s''
|picture             =
|picture_description =
|country             =Soviet Union
|test_site           =[[Semipalatinsk Test Site]], [[Kazakh SSR]]
|period              =August 1953
|number_of_tests     = 1
|test_type           =[[Nuclear weapons testing#Types|Atmospheric test]]
|device_type         =[[Boosted fission weapon|Boosted fission]]
|max_yield           =Total yield {{convert|400|ktonTNT|lk=in}}
|previous_test       =''[[RDS-3]]''
|next_test           =''[[RDS-4]]''
}}
'''''RDS-6s''''' ({{Langx|ru|РДС-6с}}, from the Soviet codename for their atomic bombs {{Langx|ru|'''Р'''еактивный '''Д'''вигатель '''С'''пециальный|lit=special jet engine}}; American codename: '''Joe 4''') was the first [[Soviet Union|Soviet]] attempted test of a [[thermonuclear weapon]] that occurred on August 12, 1953, that detonated with a force equivalent to 400 [[kiloton]]s of [[Trinitrotoluene|TNT]].
RDS-6 utilized a scheme in which [[Nuclear fission|fission]] and [[Nuclear fusion|fusion]] fuel ([[lithium-6]] [[deuteride]]) were "[[Nuclear weapon design#Alarm_Clock/Sloika|layered]]", a design known as the '''''Sloika''''' ({{langx|ru|Слойка|links=no}}, named after a type of layered [[puff pastry]]) or the so-called layer cake design, model in the Soviet Union. A ten-fold increase in explosive power was achieved by a combination of fusion and fission, yet it was still 26 times less powerful than the [[Ivy Mike]] device tested by the US in 1952. A similar design was earlier theorized by [[Edward Teller]], but never tested by the US, as the "[[Alarm Clock (nuclear device)|Alarm Clock]]".{{sfn|Rhodes|1995}}
== Description ==
The Soviet Union started studies of advanced nuclear bombs and a hydrogen bomb, code named RDS-6, in June 1948. The studies would be done by [[KB-11]] (usually referred to as [[Arzamas-16]], the name of the town) and [[Lebedev Physical Institute|FIAN]].
The first hydrogen bomb design was the Truba ({{langx|ru|Труба}}, pipe/cylinder) (RDS-6t)).{{sfn|Goncharov|1996|p=1040}}{{sfn|Richelson|2007|p=100-101}} In March 1948 [[Klaus Fuchs]] had provided the USSR with documents of the US [[History of the Teller–Ulam design#Teller.27s .22Super.22|'Classical Super']]. In these documents the classical super was described as consisting of a gun-type uranium-235 primary with beryllium oxide tamper and a secondary consisting of a long cylinder with deuterium, doped with tritium near the primary.{{sfn|Goncharov|1996|p=1037}} The design of the RDS-6t was similar to this classical super. The difference was that the light shell of beryllium oxide was replaced by a heavy shell.{{sfn|Goncharov|1996|p=1040}} The assumption was that the deuterium tritium mixture could be easily heated and compressed, and the shock would start the thermonuclear reaction prematurely. A heavy shell opaque to radiation would prevent this unwanted preheating more than the light shell.{{cn|date=August 2020}}
In September-October 1948 [[Andrei Sakharov]], working in FIAN, came up with a competing idea of alternating layers of deuterium and uranium-238 around a fissile core (Sakharov's 'first idea').{{sfn|Holloway|1991|p=37}}{{sfn|Goncharov|1996|p=1038}} This second design was code named Sloika (RDS-6s) or 'Layer Cake' after the layering.{{sfn|Zaloga|2002}} In March 1949 [[Vitaly Ginzburg]] proposed to replace the deuterium by lithium-6 deuteride ('second idea').{{sfn|Holloway|1991|p=37}}{{sfn|Goncharov|1996|p=1039}} The proposal was based on the better efficiency due to the generation of tritium by the neutron capture of lithium and the uranium-238 fission by the 14 MeV neutrons from D + T fusion. At that time Ginzburg did not know that the cross section for D + T reaction was much larger than that for D + D reaction. In April 1949 the group received D + T cross section data obtained from intelligence gathering without mentioning the source. The large advantage of lithium deuteride became evident and the deuterium design was abandoned. Both the 'first' and 'second' idea were used in the RDS-6s. The result was similar to the US 'Alarm Clock', but there is no indication that the Soviets were aware of the concept of the 'Alarm Clock'.{{sfn|Holloway|1991|p=37}}
After the United States tested [[Ivy Mike]] in November 1952, [[Lavrentiy Beria]] sent a memo to spare no effort on the development of the RDS-6s. In the final development report from June 1953 the yield was estimated at 300 +/- 100 kilotons.{{cn|date=August 2020}}
The RDS-6s was tested on August 12, 1953 (Joe 4). The measured yield was 400 kilotons, 10% from fission of the uranium-235 core, 15-20% from fusion and 70 - 75% from fission of the uranium-238 layers.<ref name="nwa">{{cite web |url=http://nuclearweaponarchive.org/Russia/Sovwpnprog.html |title=The Soviet Nuclear Weapons Program }}</ref>
After the successful test Sakharov proposed a more powerful version of the RDS-6s, code named RDS-6sD.<ref name="wcda">{{cite web|url=http://digitalarchive.wilsoncenter.org/document/118805|title=To Comrade A.P Zaveniagin|archive-url=https://web.archive.org/web/20170811031921/http://digitalarchive.wilsoncenter.org/document/118805|archive-date=August 11, 2017}}</ref>{{sfn|Goncharov|1996|p=1041}}{{sfn|Zaloga|2002}} Attempts to increase the yield of the RDS-6s however proved unfeasible.
In December 1953, all research on the RDS-6t was also stopped after it was proven that thermonuclear ignition was not possible in the RDS-6t. Both the RDS-6s and the RDS-6t were dead ends and research focused again on a two-stage thermonuclear weapon.{{cn|date=August 2020}}
A variant of the RDS-6s was developed later, code named RDS-27. The difference between the RDS-6s and the RDS-27 was that the RDS-27 did not use tritium.{{sfn|Goncharov|1996|p=1042}} This improved the operational usefulness of the RDS-27 but reduced the yield from 400 kilotons to 250 kilotons. The RDS-27 was intended as a warhead for the [[R-7 Semyorka|R-7]] ICBM.<ref name="wcda" />{{sfn|Zaloga|2002}} The RDS-27 was tested November 6, 1955 (Joe 18).<ref name="Johnston">{{cite web |url=http://www.johnstonsarchive.net/nuclear/tests/USSR-ntests1.html|title=Database of nuclear tests, USSR: part 1, 1949-1963}}</ref>
Despite the inability of the RDS-6s to be scaled into the megaton range, the detonation was still used by Soviet diplomats as leverage. The Soviets claimed that they too had a hydrogen bomb, but unlike the United States' first thermonuclear device, theirs was deployable by air.  The Soviet claim did not fool the American scientists: their fallout analysis demonstrated to them that the Soviet device was similar to Teller's ''Alarm Clock'' concept.{{sfn|Rhodes|1995|pp=254-255}} The United States didn't develop a deployable version of the hydrogen bomb until five months after the RDS-6s test, in 1954.{{cn|date=August 2020}}<ref group=A>Five deliverable versions of ''Mike'' were built as the [[Mark 16 nuclear bomb|TX-16/EC-16]] in January 1954 and retired four months later, followed by the [[Mark 17 nuclear bomb|EC 17 and EC 24]] bombs (five and ten units respectively) in April through October of 1954</ref>
The first Soviet test of a "true" hydrogen bomb was on November 22, 1955, under the directive of [[Nikolai Bulganin]] (influenced by [[Nikita Khrushchev]]), code-named [[RDS-37]].{{sfn|Kort|1998|pp=187-188}} All were at [[Semipalatinsk Test Site]], [[Kazakh Soviet Socialist Republic|Kazakh SSR]]. Like RDS-6, it was a "dry" weapon, using lithium-6 deuteride instead of liquid deuterium.{{cn|date=August 2020}}
== See also ==
*[[2013 Russian meteor event|2013 Chelyabinsk meteor airburst]], whose estimated explosive force slightly exceeded the RDS-6s test's energy
*[[Joe 1]]
*[[RDS-37]]
*[[Soviet atomic bomb project]]
*[[Ivy Mike]]
*[[Castle Bravo]]
*[[Boosted fission weapon]]
== References ==
===Citations===
{{Reflist}}
=== Footnotes ===
{{reflist|group=A}}
===Bibliography===
*{{cite journal |last=Goncharov |first=German A. |date=1996 |title=American and Soviet H-bomb Development Programmes: Historical Background |url=https://fas.org/nuke/guide/russia/nuke/goncharov-h-bomb.pdf |journal=Physics-Uspekhi |volume=39 |issue=10 |pages=1033–1044|doi=10.1070/PU1996v039n10ABEH000174|s2cid=250861572 }}
*{{cite journal |last=Holloway |first=David |date=1991 |title=Moral Leader of a Nation |url=https://books.google.com/books?id=zQsAAAAAMBAJ&q=sacharov+second+idea+ginzburg&pg=PA37 |journal=Bulletin of the Atomic Scientists |volume=47 |issue=6 |pages=37–38 |doi=10.1080/00963402.1991.11459998 }}
*{{cite book | last = Holloway | first = David | title = Stalin and the Bomb: the Soviet Union and Atomic Energy, 1939-56 | publisher = Yale University Press | location = New Haven London | year = 1995 | isbn = 0-300-06664-3 }}
*{{cite book | last = Kort | first = Michael | title = The Columbia Guide to the Cold War | publisher = Columbia University Press | location = New York | year = 1998 | isbn = 0-231-10772-2 | url-access = registration | url = https://archive.org/details/columbiaguidetoc0000kort }}
*{{cite book | last = Kozhevnikov | first = Alexei B. | title = Stalin's Great Science: The Times and Adventures of Soviet Physicists | publisher = Imperial College Press| location = London  | year = 2004 | isbn = 1-86094-420-5 }}
*{{cite book | last = Richelson | first = Jeffrey | title = Spying on the Bomb: American Nuclear Intelligence from Nazi Germany to Iran and North Korea | publisher = W. W. Norton & Company | year = 2007| isbn = 978-0393329827}}
*{{cite book | last = Rhodes | first = Richard | title = Dark Sun: The Making of the Hydrogen Bomb | publisher = Simon & Schuster | location = New York | year = 1995 | isbn = 0-684-80400-X | url-access = registration | url = https://archive.org/details/darksunmakingofh00rhod }}
*{{cite book | last = Zaloga | first = Steve | title = The Kremlin's Nuclear Sword: The Rise and Fall of Russia's Strategic Nuclear Forces, 1945-2000 | publisher = Smithsonian Books | location = Washington, D.C. | year = 2002| isbn = 1-58834-007-4}}
== External links ==
*[http://nuclearweaponarchive.org/Russia/index.html Soviet and Nuclear Weapons History]
*[https://web.archive.org/web/20070716171251/http://www.atomicforum.org/russia/russiaweapons.html Soviet/Russian Nuclear Arsenal]
* Video footage of the [https://archive.today/20130202181122/http://www.sonicbomb.com/modules.php?name=Content&pa=showpage&pid=106 Joe-4 Nuclear Test]
* [[Nikolai Bulganin]]
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[[Category:Nuclear bombs of the Soviet Union]]
[[Category:Soviet nuclear weapons testing]]
[[Category:Cold War history of the Soviet Union]]
[[Category:1953 in the Soviet Union]]
[[Category:1953 in military history]]
[[Category:Explosions in 1953]]
[[Category:August 1953 events in Asia]]